Full Disclosure: CVE-2023-40231 / CVE-2023-40232 / CVE-2023-40233 / CVE-2023-40234 "All your mempool are belong to us"

He disagrees with Riard's description of the replacement cycle and presents an alternative approach.

Nadav explains that in Riard's scenario, Bob broadcasts an HTLC-timeout transaction with input A and input B for fees, and output X. Mallory then replaces this transaction with an HTLC-preimage transaction using input A, input C for fees, and output Y. Finally, Mallory replaces the transaction that created input C, thereby removing the HTLC-preimage from the mempool.

However, Nadav suggests an alternative approach. In this approach, Bob also broadcasts an HTLC-timeout transaction. Mallory replaces this transaction with an HTLC-preimage transaction using input A, input C for fees, and output Y. But instead of removing the preimage by replacing the transaction that created input C, Mallory uses input C to create a new transaction that does not include input A, effectively removing the preimage from the mempool.

Nadav highlights that the original scenario requires input C to come from an unconfirmed transaction, making OP_CSV_ALLINPUTS effective. However, in the alternative scenario, input C can come from a confirmed transaction, rendering OP_CSV_ALLINPUTS ineffective.

The email excerpt ends with Dave signing off.